switch and hub loop

Recently had a network outage for over an hour until someone realised they
had connected two cables from a hub into two wall ports which go back to a
cisco switch, somehow this caused a 100% network utilization loop?
Can anybody explain why this happens or how this can be prevented from
happening.

Thanks for any feedback as i just want to get a better understanding of what
actually happened here.

"BINZA@" <mark1.smith(remove this)@virgin.net> wrote in message
news:%23YFLfHf%(E-Mail Removed)...
> Recently had a network outage for over an hour until someone realised they
> had connected two cables from a hub into two wall ports which go back to a
> cisco switch, somehow this caused a 100% network utilization loop?

Yep
> Can anybody explain why this happens or how this can be prevented from
> happening.

Sending the same messages over and over until your entire bandwidth is
consumed
>
> Thanks for any feedback as i just want to get a better understanding of
what
> actually happened here.
>
>

Could you expand?







"Dana" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> "BINZA@" <mark1.smith(remove this)@virgin.net> wrote in message
> news:%23YFLfHf%(E-Mail Removed)...
>> Recently had a network outage for over an hour until someone realised
>> they
>> had connected two cables from a hub into two wall ports which go back to
>> a
>> cisco switch, somehow this caused a 100% network utilization loop?
>
> Yep
>> Can anybody explain why this happens or how this can be prevented from
>> happening.
>
> Sending the same messages over and over until your entire bandwidth is
> consumed
>>
>> Thanks for any feedback as i just want to get a better understanding of
> what
>> actually happened here.
>>
>>
>
>

It's a redundant link, or circular link. The packets keep going around in a
circle until all the bandwidth is used. It's providing two links to the
same spot, which you can't do without trunking the ports. Your Cisco switch
should be able to do trunking. More advanced switched will detect this
automatically and stop it.

"BINZA@" <mark1.smith(remove this)@virgin.net> wrote in message
news:%23UuQHwf%(E-Mail Removed)...
> Could you expand?
>
>
>
>
>
>
>
> "Dana" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>>
>> "BINZA@" <mark1.smith(remove this)@virgin.net> wrote in message
>> news:%23YFLfHf%(E-Mail Removed)...
>>> Recently had a network outage for over an hour until someone realised
>>> they
>>> had connected two cables from a hub into two wall ports which go back to
>>> a
>>> cisco switch, somehow this caused a 100% network utilization loop?
>>
>> Yep
>>> Can anybody explain why this happens or how this can be prevented from
>>> happening.
>>
>> Sending the same messages over and over until your entire bandwidth is
>> consumed
>>>
>>> Thanks for any feedback as i just want to get a better understanding of
>> what
>>> actually happened here.
>>>
>>>
>>
>>
>
>

"Andrew" <(E-Mail Removed)> wrote in message
news:uzjBc9f%(E-Mail Removed)...
> It's a redundant link, or circular link. The packets keep going around in
> a circle until all the bandwidth is used. It's providing two links to the
> same spot, which you can't do without trunking the ports. Your Cisco
> switch should be able to do trunking. More advanced switched will detect
> this automatically and stop it.

The Cisco switch is fine. It takes two switches to do it (via Spanning Tree
Protocol). Since one was a Hub,...that is what screwed things up.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

The views expressed are my own (as annoying as they are), and not those of
my employer or anyone else associated with me.
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